i'm victor blackwell. >>> the australian prime minister says he's confident four signals detected by a high-tech u.s. pinger locator are coming from one of the flight 370's black boxes. >> the signals were all detected within 17 miles of each other. here's what that means. the ten planes and 14 ships are wrapping up today's search, focused on the smallest searched zone to date, which makes you think we're making progress here. >> let's put that into perspective. look at this map of the u.s. massachusetts and connecticut here, they're highlighted in red, that's the size of the narrowed search today. now, at one point, it was the size of the entire continental u.s. >> okay, david susie, a safety analyst and the author of "why planes crash" joining us now. >> and mary schiavo formerly with the national transportation and safety board. and tom fuentes, cnn law enforcement analyst, and the former fbi assistant director. >> so, mary, you probably heard what jeff said a little while ago. you know, jeff saying, which i don't know that anybody would completely dispute. if we don't find anythi